This invention relates generally to gear changing mechanisms, and more particularly to a gear changing mechanism suitable for use with an automotive transmission incorporating two or more gear sets where it is acceptable to momentarily interrupt the power to change from one gear ratio to another.
In recent years there have been many improvements in gear changing mechanisms, including improvements related to reversible overrunning clutches adapted for use in transferring torque through a power train in an automotive vehicle. Some of these gear changing mechanisms are adapted for unidirectional transmission of torque. Others, while capable of driving in two directions, generally require mechanical elements such as cams for shifting the direction of drive or for shifting from a drive position to a freewheel position.
Such gear changing mechanisms generally incorporate elaborate drive structure, including mechanical elements for effecting a change in position of sets of balls or rollers so as to shift drive ratios or shift between a drive ratio and a freewheel position within the mechanism itself. In addition, such mechanisms generally incorporate elaborate and complicated shift elements.
The gear changing mechanism of U.S. Pat. No. 3,949,848 issed Apr. 13, 1976 discloses a pair of bidirectional roller clutches, one of which may be held in a disengaged condition while the other is released to engage for driving through an associated gear set. However, this mechanism has the disadvantage that engagement may take place when the clutch input and output are rotating at different speeds. Severe shocks to the driveline may result.